Abstract: Objective To explore the impact of smartphone utilization on the sense of loneliness among elderly people in China, and to clarify the mediating role of social network, especially family and friend network between smartphone usage and loneliness. Methods A total of 8,202 samples that met the criteria based on the data from The China Longitudinal Aging Social Survey (CLASS) (2018) were selected. Propensity-score matching and causal-mediation analysis were utilized to explore the independent and joint relationship among smartphone usage, social network, and loneliness among the elderly. Results A total of 2,099 older adults (25.59%) were identified as smartphone users. The total score of loneliness in older adults was 4.48±1.58, that of family and friend network was 7.37±2.80 and 6.39±3.20, respectively. After controlling for potential confounding variables, the model indicated that the utilization of smartphone was significantly correlated with a decrease in loneliness among older adults (ATT=-0.377, P<0.001). Further causal mediation analysis revealed positive correlation between smartphone usage and the scores of both family and friend network (β=0.460, 0.778, both P<0.001). Conversely, the score of family and friend network was negatively correlated with loneliness (β=-0.181, -0.189, both P<0.001). Both family network and friend network played a causal mediating role in the inhibitory effect of smartphone usage on loneliness in older adults, accounting for 15.35% and 12.10% of the total effect, respectively. Conclusion The rate of smartphone usage among Chinese older adults is relatively low. Smartphone usage can achieve the processing effect on older adults' loneliness through the causal mediating mechanism of expanding family and friend network via smartphone and mobile social software. Encouraging older adults to use smartphones and expanding and consolidating family and friend network through mobile social software should be considered to alleviate their loneliness, so as to maximize the inhibition effect of smartphone usage on loneliness in an acquaintance-based society.

Key words: smartphone usage, family network, friend network, loneliness, older adult